About

Jesse Jokerst is an Associate Professor of NanoEngineering at UC San Diego. His research focuses on nanoparticle-based imaging, with an emphasis on molecular imaging techniques that utilize nanoparticle contrast agents to enhance signal quality and type from living subjects. He is particularly interested in ultrasound imaging due to its high temporal and spatial resolution, and employs photoacoustic imaging, a 'light in/sound out' approach, to increase contrast. Jokerst’s group has applied photoacoustic imaging for various applications including tracking and quantifying stem cells, measuring actinides, and imaging tumors in vivo. Prior to joining UC San Diego, Jesse Jokerst was an NIH and American Cancer Society Postdoctoral Fellow from 2009 to 2013 and served as an Instructor in the Department of Radiology at Stanford University from 2013 to 2015. He holds a Ph.D. in Chemistry from UT Austin and has published more than 120 articles in peer-reviewed journals. His notable awards include the NIH Pathway to Independence Award, NIH New Innovator Award, and NSF CAREER Award.

Research topics

• Materials science
• Nanotechnology
• Optoelectronics
• Optics
• Composite material

Selected publications

• What’s on the Surface? Silver Nanoparticle Fractal Assemblies and Their Impact on Catalysis

  Langmuir · 2026-05-14

  articleOpen accessSenior authorCorresponding

  Hierarchical assembly of metal nanoparticles offers a powerful strategy to modulate catalytic performance, yet the interplay between nanoscale organization, surface accessibility, and facet-dependent reactivity remains poorly resolved. Here, we investigate how hierarchical organization of spherical silver nanoparticles governs catalytic performance by systematically correlating structure, facet distribution, and reaction kinetics. Bis(p-sulfonatophenyl) phenylphosphine (BSPP)-coated silver nanoparticles (AgNPs) were assembled into fractal (Ag fractals) and aggregate (Ag aggregate), and their catalytic activity was evaluated using sodium borohydride (NaBH4)-mediated reduction of organic dyes. Brunauer–Emmett–Teller (BET) analysis shows a decrease in specific surface area from AgNPs (138.1 m2 g–1) to Ag fractals (32.5 m2 g–1) and Ag aggregate (14.0 m2 g–1). The corresponding rate constants for rhodamine B (RhB) reduction follow the same trend (0.422, 0.278, and 0.061 min–1 for AgNPs, Ag fractals, and Ag aggregate, respectively). To probe the catalytic pathway, mechanistic studies were performed. Thiol-based surface passivation using cysteine and mPEG-SH (1 and 10 kDa) suppresses catalytic activity by >90%, while radical scavenging by p-benzoquinone (p-BQ) and metal ion chelation by ethylenediaminetetraacetic acid (EDTA) indicate a predominantly surface-mediated process involving electron transfer through radical intermediates, with minor contributions from dissolved Ag+ species. X-ray diffraction (XRD) reveals facet redistribution upon assembly, with Ag fractals enriched in stable {111} planes and Ag aggregates exhibiting broadened, low-intensity features indicative of structural heterogeneity, correlating with their lower catalytic activity relative to AgNPs. Together, these results show that catalytic performance in hierarchical silver assemblies is governed not solely by surface area but by the coupled effects of nanoscale organization and facet-dependent surface reactivity.

  PublisherOA PDFDOI

• Blood-mimicking dye phantoms for evaluating photoacoustic oximetry accuracy

  Photoacoustics · 2026-01-08

  articleOpen access

  Many proposed clinical applications of photoacoustic imaging (PAI) rely on relative or absolute measurements of blood oxygen saturation (sO2), and evaluation of oximetry measurement accuracy is crucial for assessing device performance. Available bench test methods use phantoms connected to blood flow circuits with tunable oxygenation, but these methods are complex, costly, and pose biohazard safety risks. To address these issues, we have developed stable and tunable blood-mimicking solutions using binary mixtures of commercially available near-infrared organic dyes (NIR746A and IRA980) to enable non-biological phantom-based PAI oximetry test methods. We used spectrophotometry and a custom PA spectroscopy system to characterize dye extinction and PA response at 750 nm and 850 nm, then formulated various dye recipes mimicking sO2 levels from 40 % to 100 %. We then used a custom PAI system to image breast-mimicking polyacrylamide hydrogel phantoms with embedded tubes injected with static volumes of either dye solutions or bovine blood deoxygenated using sodium dithionite. Phantom testing with dyes produced similar performance metrics to blood, with root-mean-squared difference (RMSD) values between photoacoustic sO2 and reference sO2 of 6-17 % for blood and 4-18 % for dyes, sensitivity (slope of the regression line) ranged from 0.4 to 0.7 for blood and 0.4-0.9 for dyes, and depth-averaged bias ranged from 4 % to 17 % for blood and 3-10 % for dyes. These blood-mimicking dyes may offer a simpler, cheaper, safer, and more stable approach to evaluate PAI oximetry accuracy compared to traditional blood flow phantoms. This tool could facilitate establishment of less burdensome and more reproducible phantom-based PAI test methods, ultimately expediting clinical adoption of PAI technology.

  PublisherDOI

• Machine learning for automated identification of anatomical landmarks in ultrasound periodontal imaging

  Dentomaxillofacial Radiology · 2025-01-07 · 5 citations

  articleOpen accessSenior author

  OBJECTIVES: To identify landmarks in ultrasound periodontal images and automate the image-based measurements of gingival recession (iGR), gingival height (iGH), and alveolar bone level (iABL) using machine learning. METHODS: We imaged 184 teeth from 29 human subjects. The dataset included 1580 frames for training and validating the U-Net convolutional neural network machine learning model, and 250 frames from new teeth that were not used in training for testing the generalization performance. The predicted landmarks, including the tooth, gingiva, bone, gingival margin (GM), cementoenamel junction (CEJ), and alveolar bone crest (ABC), were compared to manual annotations. We further demonstrated automated measurements of the clinical metrics iGR, iGH, and iABL. RESULTS: Over 98% of predicted GM, CEJ, and ABC distances are within 200 µm of the manual annotation. Bland-Altman analysis revealed biases (bias of machine learning vs ground truth) of -0.1 µm, -37.6 µm, and -40.9 µm, with 95% limits of agreement of [-281.3, 281.0] µm, [-203.1, 127.9] µm, and [-297.6, 215.8] µm for iGR, iGH, and iABL, respectively, when compared to manual annotations. On the test dataset, the biases were 167.5 µm, 40.1 µm, and 78.7 µm with 95% CIs of [-1175 to 1510] µm, [-910.3 to 990.4] µm, and [-1954 to 1796] µm for iGR, iGH, and iABL, respectively. CONCLUSIONS: The proposed machine learning model demonstrates robust prediction performance, with the potential to enhance the efficiency of clinical periodontal diagnosis by automating landmark identification and clinical metrics measurements.

  PublisherOA PDFDOI

• Inside Back Cover: Mechanism of hierarchical plasmonic biomaterials engineered through peptide‐directed self‐assembly

  Aggregate · 2025-02-01

  paratextOpen accessSenior author
  PublisherOA PDFDOI

• Ligand Desorption and Surface Oxidation Drive Nanoparticle Coalescence in Diffusion-Limited Aggregation

  Journal of the American Chemical Society · 2025-09-20 · 4 citations

  articleOpen accessSenior authorCorresponding

  -sulfonatophenyl)phenylphosphine (BSPP), uniquely promote DLA by facilitating partial ligand desorption and silver surface oxidation, which together enable nanoparticle coalescence and recrystallization into micron-scale fractal architectures. In contrast, thiol- and polyphenol-based ligands either bind too strongly to permit coalescence or lack the electronic features necessary to support oxidation-driven restructuring. We support this mechanism with multiple lines of evidence: zeta potential data demonstrate charge neutralization, X-ray photoelectron spectroscopy confirms the presence of oxidized silver species in BSPP-AgNP fractals, and enhanced light scattering suggests increased surface heterogeneity. Electron microscopy and elemental analyses validate the resulting architecture and ligand distribution. These findings establish a mechanistic framework for chemically directed DLA and introduce a tunable strategy for building structurally fused, hierarchical nanomaterials for biosensing, catalysis, and soft matter engineering.

  PublisherOA PDFDOI

• The impact of skin tone on photoacoustic imaging: observations and phantoms for modeling

  2025-03-19

  article1st authorCorresponding

  The major optical absorbers in tissue are melanin and oxy/deoxy-hemoglobin, but the impact of skin tone and pigmentation on biomedical optics is still not completely understood or adequately addressed. Melanin largely governs skin tone with higher melanin concentration in subjects with darker skin tones. Recently, there has been extensive debate on the bias of pulse oximeters when used with darker subjects. Photoacoustic (PA) imaging can measure oxygen saturation similarly as pulse oximeters and could have value in studying this bias. More importantly, it can deconvolute the signal from the skin and underlying tissue. Here, we studied the impact of skin tone on PA signal generation, depth penetration, and oximetry. Our results show that subjects with darker skin tones exhibit significantly higher PA signal at the skin surface, reduced penetration depth, and lower oxygen saturation compared to subjects with lighter skin tones. More recently, we have developed 3D-bioprinted skin-mimicking phantoms with skin colors ranging across the Fitzpatrick scale. These tools can help understand the impact of skin phototypes on biomedical optics.

  PublisherDOI

• Diode-based photoacoustic imaging for monitoring therapeutic response in rheumatoid arthritis

  Biomedical Optics Express · 2025-03-27

  articleOpen accessSenior author

  This study investigates the application of diode-based photoacoustic imaging (PAI) for monitoring treatment responses in patients with rheumatoid arthritis (RA). Diode-based PAI provides a non-invasive and real-time assessment of joint inflammation by visualizing changes in vascularization. We conducted the analysis based on physician-diagnosed RA patients and compared the PAI results between osteoarthritis, psoriatic arthritis, and lupus-induced arthritis. Our findings demonstrate that PAI effectively captures synovitis and vascularity and can discriminate RA from other types of arthritis as well as from healthy subjects, which is of great value for physicians in improving disease management. Moreover, we could demonstrate that PAI can detect early changes of inflammation in RA joints after treatment, correlating with improvements in clinical exams. The study highlights LED-based PAI as a promising tool for enhancing treatment monitoring and personalizing therapeutic approaches in RA management. Further research is recommended to validate these findings across larger populations.

  PublisherDOI

• Long-Term Stabilization and Storage of Peptide-Based Coacervate through Tyrosine-Rich Sequences and Polyphenol Network

  Nano Letters · 2025-11-25 · 2 citations

  articleOpen accessSenior authorCorresponding

  Peptide-based coacervates are biocompatible and tunable but inherently unstable due to weak, reversible noncovalent interactions, making them vulnerable to stress from pH and temperature. This is especially difficult for coacervates used in commercial products with low-temperature storage or lyophilization. We engineered lyophilization-tolerant nanocoacervates by incorporating aromatic tyrosine residues into oligopeptide [(YR)2R10 + (YR)2D10] and reinforcing them with tannic acid (TA). This approach leverages π–π stacking, cation−π interactions, hydrogen bonds, and electrostatic interactions to create a stabilized network. The coacervates maintain their structure, count (107 particles/mL), size (<500 nm), and morphology after exposure to ionic strength of 10–100 mM, pH 3–10, elevated temperatures of 25–80 °C, biological media, and, crucially, freeze drying/rehydration. The study confirms that all interactions are essential for recovery from lyophilization. This is the first peptide-based coacervate system with lyophilization tolerance, supporting scalable applications in drug delivery, biostabilization, and regenerative medicine without cold-chain storage.

  PublisherOA PDFDOI

• Mechanism of Cationic Peptide-Induced Assembly of Gold Nanoparticles: Modulation of Electrostatic Repulsion

  ChemRxiv · 2025-01-14

  preprintOpen accessSenior author

  The aggregation of plasmonic nanoparticles can lead to new and controllable properties useful for numerous applications. We recently showed the reversible aggregation of gold nanoparticles (AuNPs) via a small, cationic di-arginine peptide; however, the mechanism underlying this aggregation is not yet comprehensively understood. Here, we seek insights into the intermolecular interactions of cationic peptide-induced assembly of citrate-capped AuNPs by empirically measuring how peptide identity impacts AuNP aggregation. We examined the nanoscale interactions between the peptides and the AuNPs via UV-vis spectroscopy to determine the structure-function relationship of peptide length and charge on AuNP aggregation. Careful tuning of the sequence of the di-arginine peptide demonstrated that the mechanism of assembly is driven by a reduction in electrostatic repulsion. We show that an acetylated N-terminal and a carboxylic acid C-terminal decrease the peptide effectiveness in inducing AuNP aggregation. The increase in peptide size through addition of glycine or proline units hinders aggregation and leads to less redshift. Arginine-based peptides were also found to be more effective in assembling the AuNPs than cysteine-based peptides of equivalent length. We also illustrate that aggregation is independent of peptide stereochemistry. Finally, we demonstrate the modulation of peptide-AuNP behavior through changes to the pH, salt concentration, and temperature. Notably, histidine-based and tyrosine-based peptides could reversibly aggregate the AuNPs in response to the pH.

  PublisherOA PDFDOI

• Peptide-Directed Hierarchical Plasmonic Biomaterials via Diffusion-Limited Aggregation: The Impact of Surface Chemistry

  ChemRxiv · 2025-03-28

  preprintOpen accessSenior author

  Diffusion-limited aggregation (DLA) of nanoparticles provides a powerful model for studying hierarchical assembly. This study reveals how specific ligand chemistries catalyze or constrain the aggregation dynamics of peptide-driven DLA using silver nanoparticles (AgNPs) as a platform. We first functionalized AgNPs with nine ligands—phosphines, thiolates, and polyphenols— chosen for their unique interactions with metal surfaces and impact on stability and reactivity. Our aim is to pinpoint which ligands best promote fractal structure formation, providing fresh insights into the deliberate design of nanoparticles. By analyzing ligand charge, functional group, and binding affinity we uncover the mechanistic factors that drive fractal growth, oxidation dynamics, and structural stability. Comprehensive spectroscopic and microscopic analyses reveal that aromatic phosphine ligands—particularly bis(p-sulfonatophenyl)phenylphosphine (BSPP)— uniquely promote fractal assembly, whereas thiol- and polyphenol-based ligands primarily lead to non-fractal aggregates. This trend is likely due to an optimal balance of electrostatic stabilization and controlled ligand desorption. In contrast, thiol and polyphenol ligands either bind too strongly, preventing the necessary ligand displacement for fractal assembly, or lack the electronic and steric properties required to modulate oxidation dynamics. Our data confirm this mechanism: X- ray photoelectron spectroscopy detects oxidized silver species in BSPP-Ag fractals, zeta- potential measurements indicate charge neutralization, and small-angle X-ray scattering shows increased light scattering of BSPP-AgNPs, suggesting surface heterogeneity. Electron microscopy and elemental analyses further validate the architecture and its composition. By leveraging ligand engineering to control self-assembly, this work provides a versatile strategy for designing hierarchical nanomaterials with applications in biosensing, catalysis, and functional nanostructures.

  PublisherOA PDFDOI

Recent grants

• Validation of Smart Masks for Surveillance of COVID-19

  NIH · $1.2M · 2020–2024

• Therapeutic Drug Monitoring with a Wearable Ultrasound-based Sensor

  NIH · $367k · 2016–2021

• Molecular Imaging of Gingipain Activity in Advanced Periodontitis

  NIH · $406k · 2020–2023

• Therapeutic Drug Monitoring with a Wearable Ultrasound-based Sensor

  NIH · $2.3M · 2016–2021

• A Miniaturized Tool for Ultrasound Quantification of Periodontal Disease

  NIH · $190k · 2019–2022

Frequent coauthors

• Zhicheng Jin

  54 shared

• Wonjun Yim

  University of California, San Diego

  52 shared

• Yash Mantri

  University of California, San Diego

  44 shared

• Jiajing Zhou

  Peking University

  43 shared

• Ali Hariri

  École Polytechnique Fédérale de Lausanne

  38 shared

• Sanjiv S. Gambhir

  Stanford University

  38 shared

• Colman Moore

  University of California, San Diego

  34 shared

• Tengyu He

  University of California, San Diego

  33 shared

Education

• Ph.D.

  UT Austin

• M.S.

  Stanford University

• B.S.

  Stanford University

Awards & honors

• NIH Pathway to Independence Award
• NIH New Innovator Award
• NSF CAREER Award